1. Field of the Invention
The present invention relates generally to devices for determining the position of a pipeline pig in a pipeline. More particularly, the present invention involves an apparatus for signaling the passage of a pipeline pig beyond a predetermined point or points in the pipeline.
2. Prior Art
The prior art is replete with devices responsive to the position of a pipeline pig in a pipeline. However, the present invention involves a device which has an indicator which moves to a visible position when actuated by a passing pig. In one modification, the indicator is lighted.
A patentability search was conducted and the following references were uncovered in the search.
Bierman U.S. Pat. No. 5,279,251 discloses a signaling device for indicating passage of a pig, and which uses a spring biased plunger and a colored visual indicating means.
Ver Nooy U.S. Pat. No. 3,109,410 discloses a passage indicator for pipeline scrapers which uses a rotatable visual indicator as shown in FIGS. 4 and 5.
Ralls U.S. Pat. No. 4,596,204 discloses an apparatus for signaling the passage of a pig through a pipeline. When the pig passes, a flag pops up.
The remaining references to do not appear to be of any pertinence.
The present invention relates to a pig detector which is adapted to be mounted on the outside of a pipeline for the purpose of determining the passage of a pig past the point of attachment. The pig detector includes a pipe nipple connected to the pipeline and communicating with the interior of the pipeline through an opening. A trigger ball projects downwardly from the pipe nipple through the opening and into the interior of the pipeline and adapted to be contacted by a passing pig. The pipe nipple connects with an indicator housing in which a cylindrical indicator is vertically slidably mounted. Within the housing are mounted a plurality of catch fingers which are pivotal towards and away from the central axis of the housing and which are provided with catches. The trigger connects with an actuator which is positioned to bear against the sides of the catch finger to cause them to pivot outwardly away from each other when the actuator moves up vertically. The catch fingers are provided with a garter spring to urge them radially inwardly towards the central axis. The actuator is resiliently urged downwardly by an actuator spring so as to cause the trigger to protrude into the space in the pipeline. An indicator spring is mounted within the housing to resiliently urge the indicator upwardly beyond the indicator housing so as to be visible and to provide indication that a pig has passed by. A lock pin is attached to the lower surface of the indicator and is provided with a pointed end which is adapted, when moved downwardly, to pry the catch fingers apart and also the lock pin is provided with an upper surface adapted to be engaged by the catches on the catch fingers to hold the indicator totally within the housing against the action of the second spring. When a pig moves in the pipeline past the trigger and actuates the trigger, the actuator will bear against the fingers and separate them radially against the action of the garter spring to release the lock pin and allow the indicator to move upwardly within the indicator housing so as to provide a visual indication that a pig has passed. In a modified form of this invention, the indicator is provided with a battery, a strobe light and a contact strip which connects the battery with the strobe light through a reed switch. A magnet is mounted in the upper rim of the indicator housing. The indicator in the modified form of the invention is longer than the indicator shown in the prior figures, and furthermore, is translucent. When the trigger is actuated by the passage of a pig, the indicator proceeds to move upwardly as was the case with the prior embodiment. However, when the reed switch passes by the magnet, the strobe light will turn on. Thus, the indicator will not only be visible, but it will also be visible at night.